On Oct 8, 11:30 am, Adrian wrote:
The Natural Philosopher gurgled happily, sounding much like they
were saying:

I'm not a truck driver, so I don't know if that's the case or not. If
it was, I'm sure the haulage firms would be restricting their driver's
speeds - yet they aren't.
yes they are, I've seen several artics with stickers on the back saying
"this vehicle is restricted to X mph" where X is lower than the 56 mph
limit (and I don't mean the 40 mph limit on single carriageways).

Is that for efficiency reasons or for PR to try to cut back on the
"dualling artics"? I suspect the latter - because it would be FAR more
widespread, especially amongst smaller/pikier outfits - whilst the ones
who seem to do that seem to be the more "polished".

The optimum speed for heavy duty trucks depends on quite a number of
things:
- fuel consumption
- using the (expensive) truck as much as possible
- urgency of the cargo
- reaching the destination before the driver has to take a break.

Certainly some North American fleets limit their trucks to below the
legal maximum to improve fuel economy.